I can confirm the results of xrandr and dmesg|grep drm above with the same kernel and nvidia driver versions on my system (a Thinkpad P50 with an M2000M).
An additional symptom I have is that the nvidia-settings application no longer supports PRIME at all; the PRIME Settings category in the application just doesn't appear. Here's the output when I start the application. $ nvidia-settings ** Message: 15:46:31.025: PRIME: No offloading required. Abort ** Message: 15:46:31.026: PRIME: is it supported? no -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1752739 Title: PRIME Synchronization doesn't work with linux-kernel 4.15. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/nvidia-graphics-drivers-390/+bug/1752739/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
